JP2610552B2 - Cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic parts and precision parts to which dirt such as oils and fats, machine oils, cutting oils, greases, liquid crystals, and fluxes adhere, and jigs and tools used for assembling and processing these parts. The present invention relates to a method for cleaning electronic parts or precision parts), and more particularly to a method for cleaning rinse drainage generated in a rinsing step.

[0002]

2. Description of the Related Art
For removing dirt mainly containing organic substances such as oils and fats, machine oils, cutting oils, greases, liquid crystals, and fluxes present on solid surfaces such as precision parts and jigs, hydrocarbon solvents such as kerosene, benzene, and xylene; Chlorinated solvents such as trichloroethylene and tetrachloroethylene; Freon-based solvents such as trichlorotrifluoroethane; aqueous detergents containing surfactants and builders are used. In particular, electronic,
For components such as electric and mechanical parts, a chlorofluorocarbon-based solvent or a chlorine-based solvent has been used, taking advantage of its high detergency and flame retardancy.

[0003] However, a detergent using a chlorofluorocarbon-based or chlorine-based solvent has serious problems in safety, toxicity, environmental pollution and the like. In addition, hydrocarbon solvents, especially benzene and xylene, are highly toxic and are designated as hazardous substances under the Industrial Safety and Health Act.Considering the danger and complexity of handling these substances, cleaning agents Is not preferred.

[0004] On the other hand, aqueous detergents are less dangerous and less toxic than solvent-based detergents, and also have excellent detergency by appropriately selecting detergent components such as surfactants and builders. Can be made. However, since this water-based cleaning agent generally has good solubility in water, a rinsing solution after rinsing (rinsing) the cleaning solution attached to the material to be cleaned with a water-based rinsing solution (hereinafter referred to as rinsing drainage). ) Has the disadvantage that the wastewater treatment property is extremely poor. The treatment can be performed using, for example, coagulation sedimentation, pressure flotation, activated sludge, activated carbon treatment, or the like, but any treatment requires a great deal of cost and equipment.

[0005] Accordingly, there has been a demand for a method for industrially and advantageously cleaning electronic parts or precision parts without requiring such a large processing cost and equipment.

[0006]

Means for Solving the Problems Under such circumstances, the present inventors have conducted intensive studies and as a result, after cleaning with a specific cleaning agent, rinsing with 5-100 ° C. water, If the temperature is maintained at 20 ° C. or higher, oily dirt and organic substances such as cleaning agents in the rinsing liquid can be easily separated and removed. As a result, the wastewater treatment property is remarkably improved, and the rinsing after separation and removal is further improved. It has been found that the liquid can be reused, and the present invention has been completed.

That is, the present invention provides a method of cleaning electronic parts or precision parts with a cleaning agent (hereinafter referred to as a cleaning step), followed by rinsing with water (hereinafter referred to as a rinsing step). Contains, as an active ingredient, a nonionic surfactant and a hydrocarbon compound, a compound selected from poorly water-soluble alkyl esters and alkyl ketones, and diluting or evaporating the water with the detergent. 5% by weight (hereinafter simply referred to as%
), And when the aqueous detergent solution is allowed to stand at a temperature of 20 to 100 ° C. for 30 minutes, 50% of the contained active ingredient is obtained.
% Or more of a cleaning composition having a property of separating from an aqueous phase, using water of 5 to 100 ° C. as a rinsing liquid, and keeping the rinse drainage after rinsing at 20 ° C. or more to maintain the active ingredient and the organic system. An object of the present invention is to provide a method for cleaning electronic components or precision components, which is characterized by separating an organic substance composed of a dirt component (hereinafter, referred to as a separation step).

In the present invention, the cleaning composition used in the cleaning step is selected from nonionic surfactants and hydrocarbon compounds, poorly water-soluble alkyl esters and alkyl ketones as active ingredients of the cleaning agent. Containing the compound, and diluting the detergent with water or evaporating the water to make the content ratio of the active ingredient 5%.
When left at a temperature of 0 to 100 ° C. for 30 minutes, 50% or more of the contained active ingredient separates from the aqueous phase. When the active ingredient to be separated is less than 50%, the active ingredient of the detergent is not sufficiently separated from the rinse drainage after rinsing, and as a result, organic soil components such as oil stains are dissolved in the aqueous phase. It is easy to emulsify and disperse, does not sufficiently improve wastewater treatment properties, and has a large organic content even if the aqueous phase after the separation treatment is reused as a rinsing liquid, so that the rinsing effect is significantly reduced. In order to more effectively improve the wastewater treatment property and to enable the reuse of the rinsing solution, the contained organic matter must be reduced to 70%.
% Is preferably used.

The cleaning composition used here includes:
There is no particular limitation as long as it has the above characteristics and satisfactory cleaning properties.
A nonionic surfactant showing a temperature of 00 ° C. or lower, a hydrocarbon compound used for improving the detergency against oily soil, a compound selected from poorly water-soluble alkyl esters and alkyl ketones, 50 of active ingredients
% Or more. Among these, those containing 70% or more of the active ingredient of the detergent are more preferable in order to particularly enhance the rinsing property. Here, the cloud point means that when 10 to 30 ml of the detergent composition diluted 20 times with ion-exchanged water is placed in a test tube and the temperature is raised at a rate of 1 ° C./min, the liquid becomes turbid. The temperature at which the solution is discharged. When the temperature is maintained at or above this temperature, the nonionic surfactant in the aqueous solution gradually separates from the aqueous phase.

Examples of the nonionic surfactant include ether types such as alkyl ether type, alkyl allyl ether type and alkyl thioether type; ester types such as alkyl ester type and sorbitan alkyl ester type; polyoxyalkylene alkylamines and the like. Condensed forms with amines; Condensed forms with amides such as polyoxyalkylene alkyl amides; Pluronic or tetronic forms obtained by random or block condensation of polyoxyethylene and polyoxypropylene; Surfactants such as polyethyleneimine series . Among them, those having a hydrocarbon group having 4 to 22 carbon atoms are particularly preferable, and a detergent composition containing such a nonionic surfactant has an increased affinity for oily stains and has a higher detergency. In addition to the improvement, the rinse drainage after rinsing in which it is mixed shows a clear cloud point, and the drainage treatment property is particularly good.

Examples of the hydrocarbon compound include paraffins, olefins, and aromatics having a linear or branched saturated or unsaturated bond having 6 to 30 carbon atoms which are liquid at the temperature of the washing or rinsing step. And hydrocarbon compounds containing an alicyclic group. Further, examples of the alkyl esters include monoesters, diesters, and triesters having 6 to 40 carbon atoms which are liquid at the temperature of the washing or rinsing step. Particularly, higher fatty acids having 6 to 18 carbon atoms and 1 to 1 carbon atoms are preferred. Esters of higher alcohols having 18 carbon atoms; esters of higher fatty acids having 6 to 18 carbon atoms and diols or triols having 2 to 8 carbon atoms; higher alcohols having 1 to 18 carbon atoms and 2 carbon atoms
Esters with dicarboxylic acids or tricarboxylic acids of ~ 8 are preferred. As the alkyl ketones, dialkyl ketones having 6 to 40 carbon atoms are preferable. As a cleaning composition,
In addition to these components, those containing a surfactant such as an anionic surfactant, a builder, a chelating agent, a rust inhibitor, an antifoaming agent, and the like can be used as necessary.

Although the washing step is not particularly limited, for example, an immersion method, an ultrasonic cleaning method, an oscillating method, a spray method or the like can be performed alone or in combination.

The rinsing liquid used in the rinsing step is a liquid for rinsing a cleaning liquid containing a stain and / or a cleaning composition on a material to be cleaned, and more specifically, pure water for cleaning. However, from the viewpoint of wastewater treatment, it is preferable to circulate and use the liquid after separating and removing organic substances from the rinse wastewater.

The rinsing is carried out by using a rinsing liquid at 5 to 100 ° C., for example, by a dipping method, an ultrasonic cleaning method, a oscillating method, a spray method or the like. Rinse liquid temperature is 5-100
° C, preferably 20-70 ° C. A temperature outside this range is not preferred because the cost, equipment, etc., required for heating, cooling, etc. of the rinsing liquid increase.

In the separation step, the rinse liquid after rinsing is heated or cooled to 20 to 100 ° C., preferably 20 to 70 ° C., to separate and remove organic substances. In order to heat the rinse drainage to 100 ° C. or more, equipment such as pressurization is required, which is not practically useful. In addition, to reduce the temperature to less than 20 ° C., cooling equipment must be installed in summer or the like. Not practically effective. In particular, it is preferable to heat the nonionic surfactant to a temperature higher than the cloud point of the nonionic surfactant because separation can be performed more effectively. That is, when the temperature becomes higher than the cloud point, the nonionic surfactant loses water solubility, and as a result, the oily stain solubilized or emulsified in the rinsing liquid cannot be held in water, and the oily stain Floats and sinks in water depending on the specific gravity, and separates. Further, the nonionic surfactant itself loses water solubility and separates from water.

The removal of the organic substances separated in this manner, for example, nonionic surfactants, hydrocarbon compounds, oily dirt components, etc. is carried out in a rinsing drain receiving tank or a dedicated tank for separation, and the upper part of the tank is used. Alternatively, it can be performed by a method of scooping organic substances gathered at a lower portion, a method of continuously extracting organic substances, a method of using auxiliary equipment such as a separation membrane, or the like. By performing these separations efficiently, the rinse drainage is cleaned,
The rinsing liquid can be reused, that is, recycled. In circulating use, if necessary, treatment such as ion exchange treatment, adsorption treatment with activated carbon, or membrane separation may be performed to remove organic substances such as water-soluble ions and surfactants in the rinse solution.

The cleaning method of the present invention has a particularly excellent effect when cleaning precision parts and jigs and the like used in the assembling process. Here, precision parts include, for example, electronic parts, electric parts, Precision machine parts, resin processed parts, optical parts, etc. Electronic components include, for example, printed wiring boards used in computers and their peripheral devices, home appliances, communication devices, OA devices, and other electronic devices; used in contact members such as IC lead frames, resistors, capacitors, and relays. Hoop material; Liquid crystal display used for OA equipment, clocks, computer equipment, toys, home appliances, etc .; Magnetic recording parts used for video / audio recording / reproduction parts and related parts; Semiconductors such as silicon and ceramic wafers Materials; electrostrictive components such as quartz oscillators; and photoelectric conversion components used for CDs, PDs, copying machines, optical recording devices, and the like. The electric components include, for example, electric motor components such as brushes, rotors, stators, and housings; ticketing components used in vending machines and various devices; and currency inspection components used in vending machines, cash dispensers, and the like. Precision equipment parts include, for example, bearings used in precision drive equipment, video recorders, and the like; machining parts such as carbide chips, and the like. The resin processed parts refer to precision resin processed parts used for cameras, automobiles, and the like, for example. Further, the optical component refers to, for example, a lens used for a camera, eyeglasses, an optical device, and the like, and the other component includes, for example, an eyeglass frame, a watch case, a watch belt, and the like. In addition, jigs and tools used in the assembling process include, in addition to jigs and tools used in various processes such as manufacturing, molding, processing, assembling, and finishing precision components as shown in the above-described various component examples, It refers to various devices that handle these precision parts and their parts.

The cleaning method of the present invention exhibits a suitable performance particularly for cleaning liquid crystal and the like adhering to a printed wiring board or a glass substrate with residual flux. Jigs and tools are not limited to these examples, and various types of oils and contaminants that may interfere with downstream processes such as processing oils and fluxes in the assembly processing process, or reduce the characteristics of products, may be attached. The cleaning method of the present invention can be applied to precision parts and jigs having a solid surface of a certain shape. When these contaminants are mainly organic oil stains such as oils and fats, machine oils, cutting oils, greases, liquid crystals, and rosin-based fluxes, the characteristics of the cleaning method of the present invention are particularly exhibited. Further, the present invention is effective even for dirt mixed with metal powder, inorganic powder, and the like.

[0019]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Examples 1 to 4 Detergent compositions having the composition shown in Table 1 were prepared, diluted with ion-exchanged water so that the active ingredient content became 5%, and the aqueous detergent solution was heated at a temperature of 20 to 100 ° C. It was left for 30 minutes. In each of Examples 1 to 4, it was confirmed that 50% or more of the contained active ingredient was separated from the aqueous phase. In addition, the separation ratio of the active components in Comparative Examples 1 to 3 was 5% or less.
Next, using a cleaning composition shown in Table 1, a printed circuit board (10 cm × 15 c) treated with a rosin-based flux
m) [Test material 1], naphthenic mineral oil (40 ° C, 350
cSt) (1 g / m ² ) coated steel test piece (10 cm × 15 cm) [test material 2] and a glass substrate (10 cm × 10 cm) coated with liquid crystal (5 g / m ² )
[Test material 3] was washed. The washing was performed by ultrasonic washing at 40 ° C. for 3 minutes. Each plate to be cleaned after cleaning (test materials 1 to
Each of 3) was immersed in ion-exchanged water at 40 ° C., and rinsed (rinsed) while applying ultrasonic waves for 1 minute. The appearance of the rinsed plates (test materials 1 to 3) after rinsing was all good. Next, the rinse drainage solution after use was allowed to stand at 50 ° C. for 30 minutes. At this time, in the example, the organic matter was separated into an upper layer and a lower layer. This aqueous layer is sampled, its COD (chemical oxygen demand) is measured (A value), and compared with the COD (B value) of the rinsing liquid before the treatment, the organic matter separation rate [(B value−A value) ) ÷ (B value)] × 100.
Table 1 shows the results. Table 1 shows the organic matter separation rate of the comparative example.
As shown in FIG.

[0020]

[Table 1]

As is clear from the results in Table 1, Example 1
In Nos. To 4, it was recognized that the organic matter separation rate was high, and the rinse liquid obtained by separation had low organic matter because the COD was low. Incidentally, those having a separation rate of 50% or more (all of Examples) exhibited good rinsing properties even when the aqueous layer was reused as a rinsing liquid, and those having a separation rate of 70% or more were excellent.

[0022]

According to the present invention, it is possible to efficiently separate and remove high-concentration organic substances from the rinse wastewater, and to simplify the subsequent wastewater treatment process. Electronic components or precision components to which dirt such as grease, liquid crystal, or flux adheres can be industrially advantageously cleaned. Furthermore, since the rinse drainage separated according to the present invention can be used again as a rinse liquid, the amount of water used for the rinse can be greatly reduced, and the cost is excellent.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C11D 7:24 7:26) (56) References JP-A-4-122480 (JP, A) JP-A-4-68097 (JP, A) JP-A-2-63503 (JP, A) JP-A-1-210004 (JP, A) JP-A-58-34182 (JP, A) JP-A-55-47104 JP, A) JP-A-52-135844 (JP, A) JP-A-50-56744 (JP, A) JP-B-56-15792 (JP, B2)

Claims (2)

(57) [Claims] 1. A cleaning method in which electronic parts or precision parts are washed with a detergent, and then rinsed by adding water, wherein a nonionic surfactant, a hydrocarbon compound, and a poorly water-soluble compound are used as active components of the detergent. Containing a compound selected from acidic alkyl esters and alkyl ketones, and diluting the detergent with water or evaporating the water to make the content of the active ingredient 5% by weight.
A detergent composition having a property that 50% by weight or more of the contained active ingredient is separated from an aqueous phase when left at a temperature of 100 ° C for 30 minutes, and water of 5 to 100 ° C is used as a rinsing liquid. A method for cleaning electronic parts or precision parts, wherein the rinse drainage after rinsing is maintained at 20 ° C. or higher to separate organic substances composed of active components and organic dirt components. 2. The cleaning method according to claim 1, wherein the remaining liquid obtained by separating and removing the organic matter from the rinse waste liquid after the rinse is circulated and used as a rinse liquid.